本文選題：局部放電 + 在線監(jiān)測��； 參考：《華北電力大學(xué)》2017年碩士論文

【摘要】：電力變壓器是電力系統(tǒng)中重要的電力設(shè)備,但是電力變壓器通常會(huì)受到局部放電的影響而導(dǎo)致電力變壓器絕緣發(fā)生劣化和老化等現(xiàn)象,嚴(yán)重威脅著電力變壓器的安全運(yùn)行。當(dāng)電力變壓器在發(fā)生局部放電時(shí),會(huì)從局部放電源向外輻射超高頻電磁波。通過超高頻(UHF)在線監(jiān)測技術(shù)能夠有效地監(jiān)測電力變壓器的局部放電情況。本文主要以超高頻(UHF)在線監(jiān)測技術(shù)的關(guān)鍵技術(shù),即局部放電信號的去噪處理技術(shù),為研究對象而開展的研究工作。在了解電力變壓器局部放電產(chǎn)生機(jī)理和特征參數(shù)基礎(chǔ)上,分析了局部放電超高頻電磁波的產(chǎn)生以及在電力變壓器內(nèi)傳播特性,并給出了局部放電UHF在線監(jiān)測的典型方案。分析了局部放電的噪聲干擾的來源,詳細(xì)介紹了連續(xù)小波變換和FFT閾值去噪方法在局部放電信號去噪過程中的去噪原理和操作流程,通過仿真分析了這兩種去噪方法的去噪效果。此外,還提出了一種基于遺傳算法的局部放電信號去噪方法,給出了去噪方法的實(shí)現(xiàn)過程和仿真實(shí)例。連續(xù)小波變換的去噪效果與小波基函數(shù)、小波分解層數(shù)以及閾值處理方式等因素有關(guān),合理的選擇這些影響因素對于達(dá)到較好的去噪效果非常關(guān)鍵,連續(xù)小波變換方法能有效地濾除掉局部放電信號中的白噪聲。FFT閾值去噪法的去噪效果與功率譜閾值系數(shù)有關(guān),適當(dāng)大小的功率譜閾值系數(shù)可以使FFT閾值去噪方法的去噪效果達(dá)到最佳,但FFT閾值去噪方法只能夠有效地濾除局部放電信號中的周期性窄帶噪聲�；谶z傳算法的局部放電去噪方法,綜合了連續(xù)小波變換和FFT閾值去噪的優(yōu)缺點(diǎn),不僅能夠很好的抑制白噪聲和周期性窄帶噪聲的干擾,而且還能夠自動(dòng)設(shè)置優(yōu)化參數(shù),提高去噪效率。
[Abstract]:Power transformer is an important power equipment in power system, but power transformer is usually affected by partial discharge, which leads to deterioration and aging of power transformer insulation, which seriously threatens the safe operation of power transformer. When partial discharge occurs in power transformer, UHF electromagnetic wave will radiate from partial discharge source. The UHF on-line monitoring technology can effectively monitor the partial discharge of power transformers. In this paper, the key technology of UHF on-line monitoring technology, that is, partial discharge signal denoising processing technology, is studied for the research object. Based on the understanding of the generation mechanism and characteristic parameters of partial discharge (PD) in power transformers, the generation of UHF electromagnetic waves and propagation characteristics in power transformers are analyzed, and a typical scheme for on-line monitoring of PD UHF is given. The source of noise interference of partial discharge is analyzed, and the principle and operation flow of continuous wavelet transform and FFT threshold denoising method in the process of partial discharge signal denoising are introduced in detail. The effect of these two denoising methods is analyzed by simulation. In addition, a partial discharge signal de-noising method based on genetic algorithm is proposed, and the realization process and simulation example of the de-noising method are given. The denoising effect of continuous wavelet transform is related to the wavelet basis function, the number of wavelet decomposition layers and the method of threshold processing. The reasonable selection of these factors is very important to achieve a better denoising effect. Continuous wavelet transform method can effectively filter white noise. FFT threshold denoising method is related to the threshold coefficient of power spectrum. The proper power spectrum threshold coefficient can make the denoising effect of the FFT threshold denoising method to be the best, but the FFT threshold denoising method can only effectively filter the periodic narrowband noise in the partial discharge signal. The partial discharge denoising method based on genetic algorithm combines the advantages and disadvantages of continuous wavelet transform and FFT threshold denoising. It not only can suppress the interference of white noise and periodic narrowband noise, but also can set the optimized parameters automatically. Improve the efficiency of denoising.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM855

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